1. Field
The present disclosure relates to an ion irradiation apparatus for irradiating a substrate (a wafer, a glass plate or the like) with an ion beam to subject the substrate to an ion irradiation treatment, and an ion irradiation method using the ion irradiation apparatus.
2. Description of the Related Art
An ion implantation apparatus is known as one type of ion irradiation apparatus. The ion implantation apparatus includes one type configured to reciprocatingly convey a substrate in such a manner as to cause the substrate to intersect an ion beam to thereby subject the substrate to an ion implantation treatment, where a beam current is measured during the treatment of the substrate, and, when a fluctuation in the beam current occurs, various parameters of the ion implantation apparatus are adjusted so as to prevent an influence on a subsequent ion implantation treatment.
This type of ion implantation apparatus is configured to reciprocatingly convey a wafer in such a manner as to cause the wafer to intersect an ion beam to thereby subject the entire surface of the wafer to an ion implantation treatment, wherein a dose Faraday cup is disposed forwardly in a traveling direction of the ion beam with respect to a position where the wafer is conveyed within an end-station, and at a position irradiated with the ion beam. In this configuration, when the wafer is conveyed to a position non-irradiated with the ion beam, a beam current of the ion beam irradiating the wafer is measured by the dose Faraday cup. As a result of the beam current measurement, if the beam current has a fluctuation which hinders the uniform formation of a dose distribution in a plane of the wafer, a conveyance speed of the wafer is changed during subsequent conveyance in such a manner as to allow the dose distribution to become uniform.
Depending on a content of the ion implantation treatment, the number of substrate conveyance strokes can be increased. For example, in the case where an amount of ions to be implanted into a substrate (a wafer made of silicon or the like, or glass plate) is relatively large, and in the case where the substrate is subjected to an ion implantation treatment intentionally using an ion beam having a relatively small beam current with a view to suppressing outgassing from the substrate, the number of substrate conveyance strokes is increased.
As the number of substrate conveyance strokes is increased, a time required for an ion implantation treatment of a substrate becomes longer. The type of ion implantation apparatus described above is configured to measure a beam current of an ion beam irradiating the wafer, in each conveyance stroke of the wafer. Thus, the number of measurements is increased along with an increase in the number of conveyance strokes, and thereby a time required for the ion implantation treatment becomes much longer.